57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
/* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#define KBUILD_MODNAME "foo"
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#include "vmlinux.h"
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#include "net_shared.h"
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#include <bpf/bpf_helpers.h>
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/* copy of 'struct ethhdr' without __packed */
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struct eth_hdr {
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unsigned char h_dest[ETH_ALEN];
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unsigned char h_source[ETH_ALEN];
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unsigned short h_proto;
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};
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struct {
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__uint(type, BPF_MAP_TYPE_CGROUP_ARRAY);
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__type(key, u32);
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__type(value, u32);
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__uint(pinning, LIBBPF_PIN_BY_NAME);
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__uint(max_entries, 1);
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} test_cgrp2_array_pin SEC(".maps");
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SEC("filter")
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int handle_egress(struct __sk_buff *skb)
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{
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void *data = (void *)(long)skb->data;
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struct eth_hdr *eth = data;
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struct ipv6hdr *ip6h = data + sizeof(*eth);
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void *data_end = (void *)(long)skb->data_end;
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char dont_care_msg[] = "dont care %04x %d\n";
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char pass_msg[] = "pass\n";
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char reject_msg[] = "reject\n";
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/* single length check */
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if (data + sizeof(*eth) + sizeof(*ip6h) > data_end)
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return TC_ACT_OK;
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if (eth->h_proto != bpf_htons(ETH_P_IPV6) ||
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ip6h->nexthdr != IPPROTO_ICMPV6) {
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bpf_trace_printk(dont_care_msg, sizeof(dont_care_msg),
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eth->h_proto, ip6h->nexthdr);
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return TC_ACT_OK;
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} else if (bpf_skb_under_cgroup(skb, &test_cgrp2_array_pin, 0) != 1) {
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bpf_trace_printk(pass_msg, sizeof(pass_msg));
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return TC_ACT_OK;
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} else {
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bpf_trace_printk(reject_msg, sizeof(reject_msg));
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return TC_ACT_SHOT;
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}
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}
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char _license[] SEC("license") = "GPL";
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